The present invention relates in general to processes and apparatus for forming facing bricks used in building construction to provide a rough textured face simulating handmade brick, and more particularly to processes and apparatus for forming textured, rough-looking extruded brick from a column of clay advanced through a brick extrusion die wherein the face of the brick produced has an attractive artistic surface having the appearance of being old, worn and weather-beaten with discontinuities or disruptions in the surface of the brick face.
It has been known for a long time that bricks can be given a rough texture or old, weather-beaten appearance simulating the weathered and roughened appearance of old handmade brick by various surface agitating or disrupting processes. One technique which has long been proposed in the art of brick-making was to veneer the exposed surfaces with a different type of clay than was used for the major body of the brick, enabling an inferior grade brick material to be used for the body of the brick with the exposure portions having the appearance of high-grade bricks. Various methods were proposed to roughen the exposed surfaces so that the brick would have a weathered appearance, such bring being frequently referred to as "textured" bricks. Various methods have been proposed for subjecting a clay column issuing from a brick-forming extrusion die to pressurized sprays of water, steam or wet mixes of granular material to provide the weathered or textured appearance.
For example, the Poston U.S. Pat. No. 1,641,047 discloses apparatus for texturing brick wherein the wet clay column issuing from a die and moving along a conveyor belt is textured, prior to cutting it into bricks, by blowing granulated clay or other granulated particles against the surfaces by high-pressure steam or compressed air discharged through variously positioned nozzles, whereby the particles strike the plastic column forming the brick and cut into the smooth surface of the column "sufficiently to break up the smoothness thereof and produce a surface that is natural in appearance".
The Tefft U.S. Pat. No. 1,896,126 also discloses apparatus and process for texturing the surface of bricks to produce a roughened weathered appearance, by forcing the clay through an extrusion die and subjecting the clay column as it passes from the die plate to the discharge die to a textured slush or mixture formed, for example, of sand, clay, coloring matter and enough water to give it a desired consistency, so that the mixture surrounds the column and causes the exposed faces of the column to become roughened and cause some of the material to be ground into the surface of the column.
The prior Hilgendorf U.S. Pat. No. 1,783,287 proposes a system wherein the clay column passing through an extrusion die is subjected to pressurized steam admitted through a supply pipe surrounding the clay column for the purpose of lubricating or moistening the surface of the clay as it is is being split into two columns during passage through the die.
Straight U.S. Pat. No. 1,859,723 discloses a system wherein the bricks, after they have been dried, are subjected to a jet of sand from a discharge nozzle to sandblast the brick and provide an appearance of being old, worn and weather-beaten.
Also the Tuttle U.S. Pat. No. 1,977,868 discloses a process for making bricks which imitate old bricks by directing showers or sprays of water at various angles against the brick moving along a conveyor belt on which they are deposited from a brick mold.
While the above described prior art processes have produced brick with roughened textures, such have not produced antiguing, weathering or texturing effects to the desired extent and with the desired consistency, and frequently have been detrimental to the properties of the brick. Natural laminations to achieve rough textures have been used in the brick industry, but such natural laminations are detrimental to the strength and durability of the brick produced because the laminations are distributed throughout the brick body and represent weaknesses throughout the body. The texturing affects to be produced by laminations or discontinuities in the clay material should be located in such way as to not adversely effect the strength of the body of the brick. Also, it is desirable to be able to control the extent of roughness imparted to the texture or character of the face of the brick, and to have an extrusion process which textures the successive bricks differently so that the bricks are not exactly alike and thus more nearly simulate the variations in appearance resulting from old handmade brick.
An object of the present invention, therefore, is the provision of a novel process and apparatus for producing a controllable rough-looking texture on extruded brick, by creating a pressurized fluid induced discontinuity or lamination inside the clay column in a brick extrusion die just below the surface of the column, and wherein this discontinuity or lamination zone of the column is exposed to form the face of the brick providing the desired rough texture which varies somewhat from brick to brick and provides a novel texturing character.
Another object of the present invention is the provision of a brick extrusion process and apparatus as described in the preceding paragraph, wherein a texturing blade in the form of a bridge spans the clay column moving through the brick extrusion die just below the surface of the column, and is provided with water or similar fluid under pressure exiting through a slot into the flowing stream of clay to create the discontinuities or laminations inside the clay column without detrimental affect to the strength and durability of the body of the brick.
Another object of the present invention is the provision of a novel process and apparatus for forming rough textured extruded brick as described in either of the two immediately preceding paragraphs, wherein the flow rate of injected fluid may be controlled to vary the texturing from non-rough to very-rough over the span of a few bricks to produce successive bricks with different amounts of roughness or texturing.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.